I do the same forensics stuff here.. EE can be recovered from pretty easily... as can most. Terminus and MaxLLF are the hardest

Just a quick explanation of how and why.. modern drives are smart (hehe) and they use voice coils, firmware and lots of constant checks to find the center of tracks, and make sure they are perfectly aligned using the servo tracks. But magnetic materials aren't that picky - they go where the force directs then. So if a track has been rewritten many times, then erased.. the center of the track may show blank. But if you offset the read head positive or negative from the centerline, you are in an area that has only been affected by long term magnetic fields. Guess whats there...

Hi, I am selling my old computer. I wiped the drive using killdisk 3.1 several times (to make sure it worked) using USDOD 5220 (3 wipes each) to remove any confidential data. It took several hours each. I work in health care and the odd time I viewed reports on my home computer. Anyway, I reinstalled windows and hope to sell the box. Is this good enough to eliminate sensitive data?

there is nothing illegal about it - in fact its a requirement of many companies before disposal of used equipment. I use dban several times a week on drives I've recovered data from and am now disposing of